Check my sentence plz!

"For".

Thank you very much!!!!

"Sounds" ok, or 'reads' ok? There is a difference - to have it read ok takes a more formal style of writing where punctuation is critical.
It's becoming more and more acceptable to write as one would speak, leaving parts of a sentence to be understood, not expressed; and to use fragmented sentences, as if spoken in mid-conservation, are left standing alone - just as you have here.
For advertising, call 297777. The subject is 'you' (understood); the action is to "call"; the object of the call is for advertising.
But, if the subject is understood to be services provided, or information, then On advertising, call 297777. Would be correct. What is improper is that what "sounds" correct depends upon context." What reads correct is not to be a fragmented sentence for the idea must be fully expressed, and can stand alone as a complete and independent thought.

May I recommend : "Inquire about advertizing at 297777."