Need help about map commands and one more thing

Hello guys. I need a help. I've been playing dota 2 for 3 weeks,and figured almost everything out.
Only two things are still bothering me.
How do i mark a spot on map,to alert my allies there is enemy there,or we shell attack "mid" or to go roshan? I hope you understood what was i saying.
Also,something not so important. I play most games with Magina and Naix.
With Magina,as soon as i get items,i start jungling,and with Naix i'm junging from the beginning.
Some people get mad for that,so i just wanted to ask you do you guys think it's gay to farm creeps,and don't participate team fights with those heroes(i keep sayin they are carry heroes,but they are still getting mad lol)

To make a spot on the map is easy, hold ALT and click on the map where you want to ping.
To draw on the map hold CTRL and just drag your mouse around the map to draw.



Heroes like Magina and N'aix require farm to be good in lategame, if they get mad for that, they are either noobs either they blame someone else for losing. Don't worry, farm everything you can with magina and N'aix, then win the game in lategame :) Also, you can gank sometimes to make them stop crying.

Hope I helped you! :)

Yes,you helped me a lot. I gave you rep +
And btw. i think i farm pretty quickly with N'aix,since i'm higher level even then those solos on mid(let's say i'm level 14 when they are level 10-12,depends on player.)

That's good, level advantage helps a lot :)

Glad I helped. Good luck ^^