You\'ll have to do theoretical training in your mining skills until the yellow bar is all covered by a green on.
The blue bar stands for the progression poits you allready recieved. This way you can easily controll if you gathered enough experience to highten a skill level.
After training enough, just go out again and try your luck. Every time you find something like gold, or iron, you\'ll gain some practice experience for the skill, until you reach the next level. Then you can do some theory training again.
Good luck on your further way. :-)
(And next time please try reading the gane\'s guide first, or searching the forums, cause this question has allready answered before a few dozen times.)