First make sure you have added all the fields you would like to capture about your subscribers, you can edit your fields from Lists > Lists, click on the name of the list, then click Custom Fields. For each field you can choose whether it should be visible on your subscribe form.
You can find the embed code to add the subscribe from to your website from:
Lists > Lists, click on the name of your list, then click Forms
You will see HTML code for embedding the subscribe form on your website
You will also see a URL you could use to link to your subscribe form.
You may need to ask your web developer for assistance with adding the form to your website and with styling it to match your website design, but if this is too hard we recommend simply linking to the provided URL instead.
We strongly suggest that your form uses double-opt-in. Double-opt-in will send new subscribers a confirmation email with a link they must click to confirm their subscription. This ensures that each email address that is added to you list is from a real person who does actually want to be on your list. Using double-opt-in will help to prevent your emails from being blocked by spam filters.
Double-opt-in is enabled by default and can be enabled or disabled from each Lists settings. For more information see: Signup confirmation - double opt in
If you use WordPress you can use this plugin to embed the form: https://wordpress.org/plugins/simple-embed-code/
Also take a look at this topic: Wordpress integrations
