Download RSBuddy client from their website (google it), find some free scripts you'd like to use for that skill, then start up client.
In the top left corner of the client hit Settings -> Accounts. Then hit "Add" and type in the Login Name/Email and hit ok. Then click on the password box and type in your password. I wouldn't worry about the pin unless it's a skill like Fletching or Pray. Pick the reward you would want to receive from the Rewards Box. If you are member, click the members button next. And never set the breaks on! Will most likely result in a ban. Then exit off that screen and hit "Run" in the top right corner, pick your script, then your account, then the GUI settings, then you're all set up using RSBuddy. Once you're good with RSBuddy, you can upgrade to Nexus/RiD.
And you must keep your computer on while botting unless you're using a VPS.