update (1 Viewer)

I am new to MS Access & I know almost nothing about vba. ... I hv a table name F with fields F1, F2, F3, F4, F5 where 1st three are number fields & last two are text fields. In a form with textboxes: txtF1, txtF2, txtF3, txtF4, txtF5 and command button cmdUpdate, I want to update F5 in table F where F1=txtF1, F2=txtF2, F3=txtF3 and F4=txtF4 conditions staisfy. .. Kindly help with complete code.

In a bound form, F1 is always =txt1, f2,,,,, etc.
And F5 is=txt5
There's no vb needed here. Update is automatic.
What of you want f5 to be?

I need to update multiple records having same F1, F2, F3 & F4