Hair issues

My friend just highlighted my hair earlier today. We used the cap thing and she pulled hair through every hole so my hair is pretty much all one color. It's reallly light. Much lighter than I thought it would be, being that it was only left in my hair for like 12 minutes. I like it, but I just want to darken it a bit. Not brown, just darker shades of blonde.

So how would I go about doing this without screwing it up?

And also, is there any way to completely strip color from your hair and have it back to the natural color? There probably isn't, but I was just wondering.

Hi I have done hairdressing for two years, if you want to go a darker shade just look for a darker shade and do as what you did today, you should have left the colour on for a longer amount of time then that. The only way to go back to your natural hair colour is to let the roots grow out. That will bring ack the naturalness nothing else will x