Before you can edit a page, you must check-out at least one page layer, or you can set-up your Fred4 to do it for you automatically (set-up the default check-out status of layers). That's because a page in Fred4 can be edited by more users at the same time, e.g. each user can design on a different layer of the same page.
Check-out a layer
On the Layers palette, review the column In use by in the row of the current layer. If it reads <free>, double-click it: the label switches from <free> to <checked-out>.
Note: if the label reads <username>, that means the specified user is editing the layer. You cannot check-out the layer in use.
Now, if the layer was not locked, it is ready for you to edit it. All other users who try to check-out the layer now, will be rejected.
About unlocking locked layers
If the layer was locked, double-click the padlock icon, to try to unlock it. If the icon disappears, you've successfully unlocked the layer. If your lock level is too low, the warning message is displayed, explaining you that you cannot unlock such layer, as your permissions are insufficient. If you believe that you should be allowed to unlock such layer, contact your System Administrator. If you are an administrator, then use the EdAdmin4, to put your lock level to the appropriate value (Run EdAdmi4, under Security, click Users & Groups, select your user name or your main workgroup, click Edit, and then in the Lock level box, enter the value. Please note that the value 0 is lowest, and 254 is highest; value 0 does not allow you to lock anything, thus value 1 is the least for locking to be enabled).
See also
Reviewing layer editing status in Fred4
Yielding a layer to other user
Managing automatic check-out of page layers
Making specific layer current on opening