Click File-->Load new data...
Click Browse and pick a bot log file or vwtk database. Log files usually have the extension .log and the vwtk database has the extension .BDB (stands for BerkeleyDB).
If you load a file, VWTk will check to see if a database corresponding to the file you have loaded already exists. It does this by looking at the file name and simply appending .BDB to it. If it does find a file, it will ask you if you want to use the existing database or overwrite it. Overwriting will erase all data in the database, so don't do it unless you are sure.
A problem with using such a simplistic database naming scheme is that two files in different directories on your hard disk will appear to be the same to VWTk if they have exactly the same file name. As of now, this does not appear to be causing major problems for users so its unlikely it will be changed.
After that VWTk will load your data and visualize it. If you have selected a log file, VWTk will create a database for it. If you have selected a database, the data will load faster.
