I am making wordpress theme, and also got stuck on-page template making, and so i need assistance...

I would like my template to include shortcodes to customers text edit box, when selected. For instance: 3 column webpage should add: [column1][/column1] [column2][/column2] [column3][/column3]

It is possible to method to code this?

This plugin does precisely what you would like, or maybe you'd like to write one yourself I recommend the WordPress Codex, particularly this page. The code to complete what you would like is simply a little too big and sophisticated to simply slap in here and also you wouldn't learn anything helpful.