Don't be too discouraged. I had a devil of a time putting mine together, and was on the verge of throwing it out the window.
After doing it twice, that little bit of practice makes it much easier to do. I have no reservations about it now.
I use Channel Lock pliers, which make it pretty easy to put the spring into position.
Of course, you need something to hold the slide back the right amount so the pin will go in.
Don't give up. It will be fine.
Bill