SSH Explorer is a SSH Client that is no longer maintained and updated. Customers who need the latest full version can download it from here:
Latest Linux versions are disabling a key exchange method that SSH Explorer needs. Unfortunately, I'm not working on SSH Explorer any more and there won't be an upgrade to fix this problem.
A possible workaround for you is to add the following in your sshd_config file and then restart the ssh service:
Note that this is not recommended because of security issues with that key exchange method. It's explained here: https://www.openssh.com/legacy.html
I'd suggest you weigh the pros and cons before making a decision whether you'd want to do something like that.
In Windows XP the files are located in in C:\Program Files\SSH Explorer and in Vista/7/8/10 in C:\Users\
There have been reported cases where the files somehow get deleted/overwritten without the user doing anything to cause that. In those cases I usually recommend installing SSH Explorer in a folder outside Program Files. For example C:\SSH Explorer. That way all relevant files are kept in SSH Explorer's main folder and Windows doesn't move them elsewhere.