I have a small plot of land how would I make it into a free public bike parking place.?

What sense does that make, unless you just want to do something nice for the community and pay for it out of your own pocket? Because you will still owe property taxes on the lot, you will bear the costs of maintaining the lot and policing it, and the most expensive thing will probably be liability insurance. If anyone is injured on your property, expect to be sued. If bikes are stolen or damaged, expect to be sued.

If the idea still makes sense to you, then bring the idea to the local planning and zoning boards to see if they will allow it, and to learn what hoops they will make you jump through to get it done.

Speak to the local government authority where you live to see if you need to apply for permissions to do that, don't forget that will cost you money and you will also need public liability insurance too

Give it away - - deed it to a local government and restrict the use to bicycle parking

If you're the property owner you'll end up getting sued

Why would you want the liability of someone breaking their ankle on your property?

Make sure that it is zoned for that purpose.

Add some bike racks to the land.

Put up a sign that says "free bike parking".

There is unlikely any zoning that says bikes can't be parked "here"

Contact your local government, they'd be able to advise you of the regulations.