Where to start...

A simple sentence describing an activity could be like this:
Jeg sparker ballen = I am kicking the ball
Jeg = I = the person doing the activity/action
Sparker = am kicking = the activity/action - verb
Ballen = the ball = what the person is interacting with

So that makes "Jeg leser boka" = "I am reading the book"
"Jeg leser bladet" = "I am reading the magazine" etc. etc.
You can see the 3 parts of the sentence are in the same order every time...

If you want to say "He is reading the book" you simply replace "Jeg" with "Han", and you have "Han leser boka"

I = Jeg
You = Du
He = Han
She = Hun
It = Den or Det
We = Vi
You = Dere
They = De

Try to make some sentences with this, and if you want, I can correct them for you.
 
Here are some more words you can use to make short sentences:
spiser - eating
drikker - drinking
brød - bread
eplet - the apple
kaffe - coffee
vann - water
Good luck!