I would like a form that will show a graph of club member fittness
results over a time period. On the form they wil be able to add new
test results and view their proggress. How can I add test results to a
field without overwriting previous results and without having to
create a new field for each result/date. Also can the results, while
in a single field, be viewed in a chart? Thanks for reading.

Look up database normalization.  That should give you some idea of the
right way to design your database.

What you reqire is a crosstab query. Enter the improved data into the
relevant table. Select queries and automatic queries. Follow
instructions to produce. At the end you should be left with something
that resembles a table. In the view mode select PivotChart.

Ok Thanks everyone it turns out all i needed to do is create two
tables with primarykeys and link them using the relationships view.
Now now i can add multiple results for each member.