Replication problems with MS Access

I am working with a database, let's call it "X" that is saved on the network. I wanted to make some changes to the design of the main form in the database. Because I am new to Access, I copied this database onto my hard drive to have a copy to play with before making changes to the "master" that still resides on the network. Unfortunately, now I open up the copy of the database now on my hard drive, let's call it "y", and I can look at the form but I can't get into design view. I don't know what the problem is. When I use the "Database X" on the network, I am able to get into the design view of the form; sometimes I get the error that I don't have exclusive database at this time and that changes could not be saved. Does this have anything to do with the problem? Please advise. Why can't I get into design view for the main form of database y on my hard drive. Thanks.