Ignore anyone trolling you for using MechJeb. It's a single player sandbox game. They have no right to. As a relative newbie myself (only had the game a week) I can manually (no MechJeb) get into stable and near perfect orbits, land on the Mun, Minmus, return, and dock... Arguably the hardest maneuver in the game. However my laptop is old and sloooooow. So I installed MechJeb when it got to the the point where coming within range of my space station/moon base got me down to 1fps. Much better. It just allows me to do the things that would be impossible due to lag.