How to create login signup form

Answer 1

First, you have to understand form html and its properties (action, method), input (name, type, value) and server side programming for processing its form.
This is example,
<form action="process.php" method="get">
<input name="my_name" type="text"/>
<button type="submit>Submit Form</button>
</form>
And, if you want to process its form, you have to create PHP file that will catch its form value after submitting and process it.
For example,
$name = $_GET['my_name'];
echo "$name;

Answer 2

olá! alem das linguagem html, js, e css você teria quer usar php ou outra linguagem server-side para validação de user. para user-side você faria um formulário normal com html, editaria estilo com css e caso necessite, faria validação de caracteres com js...