well first of all. i seem to have a lot of problems with coming up with sentences or forming sentences in general. for example when i'm talking to americans or whatever i usually don't really know what to say. but i fully understand them!! and when i'm about to say something. it's almost as if i didn't know any words.. like. i don't know any other english words other than the basic stuff. how can i improve?? please help me. thank you
Looking at your responses it seems that you have a good grasp on the english language. Which is good! It means you have all the tools available to you when making conversation. You probably just need more practice. Conversations in non-native languages can be difficult, because you have to come up with an answer on the spot. It's not impossible, though. You'll probably stumble for words and make mistakes at first, but that's perfectly normal and okay.
tl;dr: talk more. Good luck!