Did you almost fall over because it was too heavy or because it felt awkward?

If it was too heavy, then I agree with @xcaly - see if your gym has lighter barbells. If they don't, or if those are too heavy, you can definitely use dumbbells. For squats, do goblets squats. They won't feel the same because they're essentially a front squat, but it will help you get used to the range of motion and build up some strength. Same with the other lifts. Try to use the barbell, but if you can't, dumbbells are OK until you can move up to 45 lbs.

If it was just awkward, ask someone who works at your gym to help you. Or another lifter. And watch lots of videos on form.

Good luck!

what @crabada asked is a good point. i'm remembering how barbell squatting felt really freakish and counter-intuitive to me, because i was squatting 'without' hands. every instinct you have tells you you need your hands free to stay safe if you're moving, especially in the kind of pattern a squat has. so having my hands tied up with a heavy bar felt scary because my brain was going 'you fall over, you're going to go down.'**

i'm glad i persevered though. the thing is, you're supposed to squat in a straight up-and-down path right over your centre of gravity, and i feel like not having any hands to cheat with actually taught me how to do it.

** this is what your brain thinks at first, but it isn't actually true. you might find some reassurance by checking out youtube for clips on 'how to fail squats'. most people don't even fall over. they just kind of jump themselves forward and let the bar do the falling, behind them.

Try practicing the movements with a pvc pipe or shower rod.

I can't understand why people always recommend to use machines first. They don't teach you the proper free weight movement. Perhaps the gym staff is trying to justify their investment in equipment.