Synchronizing movement in clients and server

So im trying to get into game making and my foundations in coding specially networking are a bit...lacking. Right now im atempting to make a smal multiplayer game and as the title sugest im trying to sychronize the movement of the player in the client and the server and i know i should be using a Network transform instead of Rpc's to do it but since i'll be using rpc's for other stuff(i think) i thought i should get used to working with them and do a bit of rpc's and later do things proper.When it comes to moving around in 2d all seems well but when it comes to jumping i have to repeatedly mash the jump button and the jump isnt of consistent height plus some ocasional jitters on the jump...so yeah help pls and sorry for the long text

 

so the non responsive thing was because i was runnig everything on fixed update, cut and pasted the input code into update and works much better, still stutters tho