linking internal

Do you mean links within the text of a page? If so the CF Internal Link Shortcode is useful.

Depending on whether you want links to Posts or pages – you don’t seem sure – You can use a pages widget or recent posts widget in your sidebar

It sounds like you need to do a bit of reading & exploring to familiarise yourself.

Start with these:
Glossary: http://codex.ww.wp.xz.cn/Glossary
Getting Started: http://codex.ww.wp.xz.cn/Getting_Started_with_WordPress
Pages: http://codex.ww.wp.xz.cn/Pages
Posts: http://codex.ww.wp.xz.cn/Writing_Posts
Widgets: http://codex.ww.wp.xz.cn/Appearance_Widgets_SubPanel