The steps you need to follow are :
1) First of all, do not cancel your account at the present hosting company you host yoru site, until the transfer procedure to Papaki is completed.
2) Download all of your files from the old server and upload them with FTP to the new one at Papaki.
In this step, you need to transfer as well the databases you might use. You will find all necessary information on FTP & Plesk access from where you can create databases, inside the hosting management email you receive to the admin email you have added to your account, right after your order payment.
3) As soon an all files and databases are transferred, you can check through the temporary URL given, whether the website works properly.
4) Log in to your Plesk and create the email accounts you use.
5) Change the Nameservers of yoru domain and insert the ones sent to you by email, the one with all hosting management information.
You can change the nameservers throough the Control Panel of the company you have registered your domain with. Right after you change them, you need around 4-48 hours in order for the site to open from our servers. Meanwhile, your site will be accessible and opening from the old server. After 48h more or less, you can cancel your old hosting at your old provider.
Remember that you can contact our Support Department in case you face a problem during your site transfer. Finally, we would like to inform you that our Support Department can transfer your website for free.