How to create triangle mesh?

Hello everyone. I am a beginner in 3D.
How can I make something like this in SketchUp http://s18.postimg.org/i0uq3txix/Screenshot_2015_11_03_00_08_27.png

Check out the Sandbox Tools extension.

Activate the extension via:
Window (menu) > Preferences (dialog) > Extensions (panel)

Turn on it’s toolbar via: View (menu) > Toolbars (dialog)

Search this forum about Sandbox Tools:
http://forums.sketchup.com/search?q=sandbox%20tools


Search the Extension Warehouse for other mesh extensions:
http://extensions.sketchup.com/en/search/site/mesh

… or from the Extension Warehouse window within SketchUp, type “mesh” in the EW search box and press ENTER.

You can have a look at the plugin Artisan (39 USD): http://artisan4sketchup.com/