Find Records in Subforms

I have two tables (Credit Card Log and Vendor Information) in my database.
Credit Card Log is the main form and Vendor Information is the embedded
subform in my main form. I would like to find a vendor name, which is located
in my vendor information table (subform), by using a command button on my
main form (Credit Card Log).
Vendor Information.Vendor Name is specific to each Credit Card Log record
and will not search beyond that. I would like to be able to search a vendor
name to pull up the corresponding Credit Card log record main form.
I have the 2 tables linked by Purchase Number, which is unique for each
credit card log entry...tying the vendor information table to the credit card
table.
I am not very knowledgable in VBA...so please use lamens terms.