Hello to you ALL
We build a new website to replace the old website. Any tips how I can handle the full test situation?
Only that you know I am the only tester in the company and I would like to do an great job when we deliver the new website into the production.
I have already an automation for the old system this needs to be converted or written new .
Thanks for your help and support
Silvi
So it has to work as before - just in a new way? 
Start to define and record what is “as before”… functions, performance (Site Speed Tools), etc. make it explicit and use it as an agreed baseline.
Then run the whole thing again after cut-over.
If at all possible, have the old site still running while you are testing the new one, and do not allow the old site to be switched off until testing is complete so that when you find things not working as you expect you cna check exactly what the old site did. Otherwise you can reach a point where everyone has forgotten exactly how the site used to work, and if the original requirements weren’t written down you may lose functionality that users are expecting.
If that’s not possible, fully document what the site did before (I would recommend taking standard routes through the site and taking lots of screenshots) to provide evidence of what the current users of the site will still be expecting to see.
Of course, it may be that part of the upgrade to a new website does involve changes/improvements to the way it works, in which case I would expect some indication to the user of what has been improved, and would split my testing between things that have stayed the same (with a direct comparison to the original) and things that have changed (which will be like testing new functionality on the old site).
Hopefully, there’s a statement of why they built the new site and what problem it was trying to solve. I agree with the need to record what was there before, especially if it’s not going to be accessible after the switch.
Then comes a lot of questions is this a member site? Is there legacy info that the company has chosen not to bring forward to the new site? Have they extended the site to mobile devices, is that actually fit for purpose?
Same data sources? same middleware? It’s likely not the same but they could make that claim:) I would treat this , time-willing, as a new site , just one that we as testers would have a lot more information about than would usually be the case.
How you can handle it? With patience and determination. What sort of tips do you want? It’s like going up to John Williams and saying “Hey, I’m a composer too, any tips on my next concerto?”. It’s so wide a question that the answer will be “drink plenty of water and get a good night’s sleep”. Well, actually, it’ll probably be something better than that, John Williams is a clever guy with a gentle, poetic manner. He once said “It’s not hard work that makes success - it’s sustained hard work that makes success”. I’m hardly the John Williams of testing, but you see what I’m saying.
John Williams also said “My attempts to try to support these films, and reach people through what they hear, is mostly an intuitive thing. The application of the modulartory structures of music and so on - manipulations, if you like. Music for me is really like sculpting. You take a chunk out of the stone, and another chunk, and finally it reveals itself. What’s in the stone we didn’t know when we began - we will find it”. Maybe all you need is the confidence to tap into your intuition and experience to roll with the shifting, exploratory path through the landscapes of test strategy and context-driven risk analysis.
He also has said that he asks himself what the texture and tone of a film is before he begins crafting a score. Maybe you should feel the texture and tone of your website and it will help you craft something beautiful.