I am new to Libre Office, and want to transfer lotus spread sheet files created with Lotus SmartSuite 9.8.1 running Windows Vista. I now run under Windows 10 which will not run Lotus. I understand that Libre Office will handle Lotus files and I need instructions on how to do that. Thank you.
Start LibreOffice then File → Open → navigate to the file → mark it → open.
Be Happy. 
Speaking from own experience, the transfer will not be perfect. The best thing to do if you can is to export your files from Smartsuite as newest available .XLS files and than import/load them into LO. This way you have the least problems.