Help Needed With Form

Apologies if the answers are very simple, I'm a wee bit of an Access newbie!

I have created a form with which I am going to record gym attendances for my members in my members table. When I do this it will update a table 'gymattendance' which stores the information about price paid, date, memberID etc.

My first problem is that despite 'tblgymattendance' being linked to 'tblmembers', when I go to record a gym visit in my form, it will only allow me to enter new members, rather than select current members to record a visit. How do I get around this?

Once I get that sorted, I need the form to then send that record in its entirity to a new table, 'tbltakings,' which stores information on all the gym sessions attended to calculate total moneys taken from those sessions. I have been unable to find a way add records to 'tbltakings.'

If the latter is not possible, would a simple update query work to add to a field of 'totaltakings,' in 'tbltakings' ?

Many thanks in advance this is really starting to get on my nerves!!!