Once you have a MindTerm session started you can continue to use your browser without interfering with your SSH session. Your SSH session will, however, be terminated if you exit from your web browser.
Depending on the configuration of your web browser, you may be asked to "grant permissions" to the MindTerm client before actually running it. If prompted, please grant the client the requested permissions -- without full permissions to use the network, MindTerm can't function, and without permission to write to your local disk drive, MindTerm won't be able to save any configuration settings you change during your SSH session.
Please note that MindTerm requires your browser to be configured to support Java. Please also note that some older versions of popular web browsers like Netscape and Internet Explorer do not support Java applets, nor does the (ancient) Microsoft JVM, so ensure that you're using a Sun JVM.
The MindTerm SSH client also supports an SFTP client --- look under the