1st off, it's kinda sketch that you recieved something that you didn't purchase. Without too much skepticism i'd contact the seller (if available) and get what you wanted, which in your case, clenbuterol.
Your last post you are asking what to supplement with clenbuterol?
Easy, You'll need Taurine so you don't get muscle cramps, you'll need 1.5-2 gallons of water... fuck i dont wanna type anymore
DO A SEARCH on CLENBUTEROL FAQ .. on this site, everything u need
oh and u wont crash hard from clen... i crash harder from a cup of coffee and a redbull per say