New to hair dying: please help!

Is your hair virgin, or do you have it dyed/highlighted?

If it is virgin, yes you will need to bleach.  If it is already pretty light, then just a 10 vol bleach bath should do the trick to open up your cuticle and allow the dye to stick.  If it already dyed, it should be porous enough already.

You never mix bleach or peroxide with semi permanent colors.  Bleach first, wash it out, then apply the dye.  Since you are already blonde, you shouldn't need to leave the bleach in very long - I'd say around 15 minutes.

If you want it to last a long time, then leave the dye in as long as you can stand.  At least an hour.  I leave mine in overnight.

There are quite a few great brands out there.  Since you are in the US(me too!) I highly recommend Punky Colour.  It super pigmented and long lasting.  You can dilute it quite a lot with conditioner and still get vibrant color, so it is quite economical.  Manic Panic is OK.  They have nice colors, but it is expensive and not very long lasting.  Plus you have to apply it neat to get vibrant color.

Yeah I dyed my hair light blonde a week and a half ago. Thanks for suggestion the hair dye brand to me. Manic Panic does have a lot of choices but I wasn't sure if other brands existed. I'll try the brand you suggested out to me and I'll be sure to post up my photo as soon as I get done.  ;D

If you've dyed your hair light blonde, then you've bleached it already and there's no need to do more processing.

Apply the semi dye on freshly washed, unconditioned hair and leave on for as long as you can stand it.

Oh okay, I usually see videos where people don't wash their hair but this makes a lot of sense.

Man I sound like such a dork right now. I've only dyed my hair using boxes that you can usually get at the store.

I sent you a pm asking another question before I wrote this.

And this is totally different question but how many different semi permanent brands are there?

I only know of Manic Panic, Special Effects and Punky Color. Is there any others?

Yes, there is also Adore, Pravana, N'Rage, Ion Brights, La Riche Directions, Crazy Color, Stargazer...I'm sure there is more.

Oh okay, I usually see videos where people don't wash their hair but this makes a lot of sense.

You should always bleach or use permanents/demis on unwashed hair--the longer it's gone unwashed, the better!  It's because of the chemical reactions between your hair and the peroxide.  Bleaching or using permanents on freshly washed hair is a bad idea--you risk fried hair and scalp burns.  You also must adhere to the timing instructions, as again, a prolonged chemical reaction is generally a bad idea with skin and hair.

Semi dyes, though, are different.  They work as coloured conditioners and stain the hair, so anything actually on the hair can block the uptake of dye, including your natural oils and any products or conditioner.  As they don't have a chemical reaction that changes the structure of your hair, they're safe to leave on for hours, even days if you so desired, as long as you don't have an allergy to the dye (allergies to semi dyes are pretty rare, though--usually it's permanent dyes people have problems with, so they switch to semis because they tend to be safer.  Always patch test to be sure, though!).