I don't understand something about skaven magic,skaven mages get power and dispell dices as normal(so a grey seer get 4pw and 2 Ds dice and an engineer gets 1of both) or they have to use warpstone dices and get only the basic ones as normal dices or what else?

Skaven get the casting and dispel dice as normal, so as you said, a grey seer gets 4 power dice and 2 dispel dice. Warlocks are slightly different; they count as Lv1 mages but can have an upgrade to give them an extra casting dice (as well as other goodies to effectively make them a Lv2 mage).

A grey seer gets 4 warpstone tokens, and a warlock a single token. You may buy more from the magic item list (brought rather like scrolls). These are one use only items and count as an extra casting dice. But if you roll a 1 when using that dice you take a wound, with only a regeneration roll allowed.

Owaria