I can't seem to increase my weight on bench press. My sticking point is at around half way through the movement. (I can get theb weight off my chest no problem, but cnat't get it past where my arms are at or a little over 90 degrees). I think my shoulders are extremely weak as I haven't had a professionally structured program before(doing the 12 week challenge now). 

Could my sticking point be due to weak shoulders? (Or triceps?) If so, would working shoulders twice a week be too much? I really want to get past my bench plateau.

I train OHP, shoulder press and arnold press for my shoulders (and other stuff that wouldn't impact my bench)

and dips, pushdowns, overhead extensions and close grip bench for my tris.

I have the exact same sticking point. Try getting more speed off your chest in order to get past that sticking point. At least that's what has worked for me in the past. Also, try to engage your lats and train your lats harder! they're super important for that point in the bench and I know I could use more lat engagement.

Best of luck getting past that plateau!

Stronger front Delts and Tris will definatly help your bench. Form is important like stated, pushing through your heels on the way up help. If you can't increase the weight try and add reps that's what I do then after a couple seshes drop the reps back down then increase weight.

Hi, when I'm doing presses, I feel like I'm not activating my chest but am using my shoulders instead. How do I fix this?

Your front delts will be used to a degree. If you have your arms at 90 degrees instead of 45 degrees you will feel stress more on the shoulders. Also as you bring the weights up squeeze your chest more and concentrate on mind muscle connection.

I just went to the gym the first time, and I bench pressed the fisrt time.

The trainer told me to widely open my arms at least onw-arm length. when I was doing it I felt nothing in my chest but burning on my shoulders.

I asked him if I was doing it wrong but he said my shoulders and arms are not strong enough. I do not know if he was right because he also told me I should workout EVERY SINGEL DAY and will get ripped soon, what a BS.

I was benching 0kg, just the bar, was I doing it wrong or just weak shoulders?

Since you're new, it could just be weak shoudlers or something like that. However, I would argue that if you're using your shoulders that much to get burning, you're probably not in the right position. You want to retract your scapula to generate a solid foundation so that you can press up. Also, if your shoulders are not retracted, they can easily take over the movement (this is what I'm guessing happened to you). Additionally, try to hold the bar so that you're not excessively wide. I'm 6'1", with the same as my wingspan and hold the bar with my pinkies about half an inch inside the rings. This set up uses more tricep than a wider grip, but it helps me bench more weight which is what I'm after right now.

Look for form videos on the internet and try them out to see how you can fix this. (I like Alan Thrall's channel and Brian Alsruhe's as well for form videos. I find that they break the cookie-cutter form videos everyone makes and actually explain the mechanics involved, which works great for me).

As far as mind-muscle connection, I would suggest using dumbbell flyes so you can feel the chest stretching and contracting and thus generate that connection and can exploit it later on!

best of luck!

English is not my native language, this sentence I do not quite understand:"I'm 6'1", with the same as my wingspan and hold the bar with my pinkies about half an inch inside the rings."

Are you saying you grab the bar very wide that your hands are just half inch away from the disks? Or just my misconception. That is so wide, is that the world of being over 6 feet? Damn every thing is smaller.

Nono, you did misunderstand a little bit. I am 6 feet 1 inch and my wingspan is the same. However, by 'the rings', I mean the little rings that are marked in the barbell. Here's a picture so you get a better idea. Some barbells won't have this, but a large majority of them do! (it's also not a standard barbell in the picture, but it's the best pic I found easily on google, haha) I do a pretty narrow grip despite being pretty tall and having long arms. This allows me to use more triceps and flare my elbows a little bit when I get to the sticking point of my bench in order to engage my shoulders more and continue pressing the weight up

Oh I see, that makes sense. yes it is very narrow and the triceps are more participated