Yesterday at work there was a girl that asked me for a number, she was with two friends of her and she shyly asked if she can have my number. So I gave her my number by texting her once saying hi. And I went back to work. My question is, should I text her first? And what should I say?

I'd wait to hear from her.

If you don't hear in several days, then I'd text a "hi" back to her.

Does she connect the text with your name/face?