^ this.
It sounds like you missed the shot. Even if you register and draw back blood the needle tip can still slip out of the vein as you inject, especially as you are new to it and it's tricky holding the needle completely still and in position while you inject the drug. Did you use a sterile prep technique? The main risk is infection (signs are heat, redness, swelling and soreness) or tearing the vein causing a haematoma (bruise) under the skin. If you are at all worried about it, get yourself to a doctor as you may need antibiotics and are at risk of developing an abscess..
Hand veins are tricky as they are smaller and more mobile under the skin - definitely not first choice. Start at the crook of the elbow where the veins are bigger and more stable, rotate your sites, use a good technique and only progress to forearm then hand veins if you really have to...
As misspharmacyashley said IVing is a long and dark bath to be embarking on.. maybe this is the wake up call you need? However, if you decide to carry on IVing, please have a read on BL (especially on the Other Drugs forum) about safe IV technique and don't be afraid to ask if you have any questions. We'd all rather you did it safely - tis the whole point of a harm reduction forum!
A quick search revealed
this IV complications megathread which should give you plenty of advice
edit: also have a look at
this guide to safe IV injecting
I'm going to close this as I think you either need to get medical or advice, or if not, you don't really need us in BDD - what you do need is to do is some research about the dangers of IVing and how to do it as safely as possible

send me a pm if you disagree with me closing it..