update access through vba and excel userform

[tinybears]

Hey can someone help me with forming a code. I have some userforms in
Excel and an access database. I want:

If Ticker already available in database(access) (help with this
please)
Messagebox("Already available")
if Yes then
Messagebox("Do you want to overwrite the data?", VbYesNo)
if yes then
'delete the records and write back the new records(help
with this please)
else unload Userform
end if
else 'my regular code
else
'my regular code
end if


thx a lot. I'm becoming desperate with this problem.
If someone needs my code I'm glad to send you my whole workbook. It's a
workbook for forming financial ratio's for stocks and also graphs and
such.

thx