My dog is sick!! what can i do?

i got home from school and i didnt see my dog i didnt really think much of it but an hour later i found her hidden outside under a small tarp and shes usaually all excited and jumping around when i come home but she wasnt moving till i picked her up- and gave her some water :/ but after that she just threw it up im really scared!! she wont move or anything shes just slumped sleeping and vomiting! what can i do to help her!! and i know she is sick becouse shes not eating and is weak :[