A relational database is basically two or more tables in one database which have a field that links them together in some way. It allows you to group common data without data redundancy more or less.
Here or some basic instructions (it depends what version of access you have):
1. open microsoft access
2. make a new database
3. create your tables which each are made to hold data which is common
4. in 2003 access, right click in the list which gives you your tables to choose from, and click relationships, then link the fields which are being taken from other tables (they are called foreign keys). In 2007 access, click database tools and then relationships.
5. link them together, you will know this has worked by the fact that the related field in the table is linked with a line to the corresponding field in the table it came from.
6. insert your mock data
7. done? lol
Hopefully that helps you understand.