If I have a 1 or 2 in instruction but a 7 in another skill, can I teach someone my level of skill or just some of it?

Well, first, Kudo's to you for taking a skill that, as a runner, is largely impractical. But, onfortunately no. All the instruction skill does is provide extra dice based on your successes to the student. Since the person learning a skill doesnt make a test, the instruction dice arent used anywhere (barring GM house rules)

So, lets say you were a mage, and you Johny Fireball wants to learn how to cast stunbolt, cuz he just got fragged by a spirit. You know stunbolt, so you offer to help him learn it. You roll Charisma + Instruction, and get say, 2 hits. Those 2 hits equal 2 extra dice he gets to make on his spellcasting + intuition test to learn the spell.

You can Instruct someone else in the Skill they wish as long as your rating in that Skill is at least 3 and is equal to or higher than the rating the student wishes to achieve.

For every 2 hits you get in an Instruction + Charisma test, your student gets 1 extra die in his test to learn the Skill at the new rating. (see SR4A, p. 134)

well in sr4, i dont see any rules for the mentioned learning test...

For spells it is in the SR4 book already for everything else it should be in the errata.

Ah, ok it is there.. sorry, then yes, you can, but it's not a huge benefit