I have itching welps on my hands?

Contact allergy. This could represent allergy to something you touched. Cold compresses can help initially. Claritin (loratadine) or surged can decrease symptoms. If these measures are inadequate see a dermatologist for evaluation, possible allergy testing and proper treatment.
Many possibilities. There are many things that could cause the skin to itch. Several types of inflammatory conditions of the skin, allergic reactions, and sometimes bacterial, viral or fungal infections can cause rashes on the skin. Insect bites can also be the cause of a rash on the skin. Have it evaluated by a professional and get the appropriate treatment.