What do members see when they log in?
They will see a Page that you create in WordPress, which can link to other areas of your site that a customer has purchased access to. In addition, it's a good idea to embed the
[s2Member-Profile /] shortcode so a user can update their account details. This allows them to change their name/email for instance.
See also: Customizing Your Login Welcome Page
What Exactly is the Login Welcome Page?
A Login Welcome Page (in the context of s2Member), is a Page you create in WordPress (like any other Page). Then you designate it as your Login Welcome Page when configuring s2Member. This can be configured (or reconfigured) under s2Member → General Options → Login Welcome Page. It's the page where a user/member (anyone who can log into your site) is redirected to upon logging in.
Most Common Use of the Login Welcome Page
Often times, the Login Welcome Page that you configure with s2Member will serve as a customer's "My Account" page, or something similar. Most site owners will use this page to introduce links to important areas of their site, so that users can gain access to whatever it is you've sold them. This makes it easy for a customer to find what they've purchased, and to locate information associated with their account.
Some site owners will also insert the
[s2Member-Profile /] Shortcode into this page. Or, they might choose to insert a link that takes a user to a separate page which contains the
[s2Member-Profile /] Shortcode. The
[s2Member-Profile /] Shortcode produces a Profile Editing Form. Users can update their profile on your site (i.e., name, email address, any custom fields you've configured, etc). You can learn more about this Shortcode here. See: WordPress Dashboard → s2Member → General Options → Profile Modifications
A Unique Login Welcome Page for Every User?
Obviously, not every customer will have access to the same content or services you offer. Maybe you've restricted content with s2Member in different ways, at different Membership Levels, or with different Custom Capability packages. If someone logs into your site as a Free Subscriber, you might want to show a Free Subscriber something different than you show a Member at Level 1. If you always display links to content that requires Membership Level 1, but it's a Free Subscriber who logs in; those links may not work for them. So let's not show those links to a Free Subscriber.
To accomplish this, site owners will typically use
[s2If /] (Simple Shortcode Conditionals) in their Login Welcome Page (provided by s2Member). In this way, you can tailor the content/links displayed on the Login Welcome Page to specific users (e.g., Free Subscribers, Members at Level 1, Members at Level 2, Members with a particular Custom Capability, with a particular username, etc). You can learn more about Simple Shortcode Conditionals here: WordPress Dashboard → s2Member → API / Scripting → Simple/Shortcode Conditionals