Pick a name that isn’t a trademark.
Create Memorandum of Association document (Company name, what’s the purpose of the business, how it will be run, shares issued, legal guff basically)
Create Articles of Association document (Legal stuff about shareholding).
Register company.
The actual shares don’t need to be paid for. Just declare the issue. Payment comes if you ever want to sell them.
If you have more than one shareholder, then you legally must pay the share of dividends to each based on the shareholding.
Templates for the documents are easily available, but make sure the wording is legally correct and up to date with current regulations and laws.
Alternatively just pay an accountant to set it all up. Price will vary wildly, though think mine was a peanuts amount, but on the basis I’d be using them as accountants. Was a package with company set up and bank account.