You can access the proposal pool (also known as the Translation Memory) as follows:

As of Release 4.5A, the proposal pool is a dialog box. This means that you may not see all of the source text and target text in cases of texts longer than 50 characters, for example. You can use the horizontal scroll bar at the foot of the dialog box to see the rest of the respective text.
See also:
Displaying the Proposal Pool for an Object in SE63 Creating a List of Terms in Proposal Pool Maintenance Proposal Pool Administration