How to upload previous issue to new site

hello, we just recently install OJS
we need to add all our previous issue which they were in pdf format
how we can do that


You can create issue and start uploading via QuickSubmit plugin or in a usual way as submissions.
When you create journal you can sey that is for example Vol. 1 No. 1 1985. and start upload and when you finish you publish and do others in teh same way.
I have uploaded in that way issues published in teh last 45 years of one journal.