Help needed - how are people building amazing things?

Update- thank you everyone who has posted! I will sit down later and try out the tips & tricks

So I've had planet zoo since release (PC). I have only played career because I do not have a scooby how the controls work to build sandbox and franchise.

Frustration levels hit an all time high last night when I spent an hour trying to build a measley 3 arch walkthrough.

Please if someone has a non-frustration guide that would be helpful! Or am I just doomed?

(Probably been asked lots, but I am desperate to play and as you have figured out, I do not have the greatest of patience)