I ask her for her phone number? she gave me it? then I send her massage but she didnt reply?

I knew her at my university ? am senior and she is fresh year? I saw her and i LIKED HER? so after awhile she came by me so I said? hi......... how ru ? ...etc then i asked her her phone? she gave it to me? and when I send her massage on Friday? until now she didn't reply? why>? what should i do? give her a week then call he? or what? I liked her and I want her? so plz give me the right steps? to get her? thanks!