You can use SqlRoleProviders and SqlMembershipProviders with the .NET default management, or you can write your own providers.
http://www.odetocode.com/Articles/427.aspx
http://msdn.microsoft.com/en-us/library/aa478949.aspx
Then these are used in conjunction with asp .net forms authentication.
<authentication mode="Forms">
<forms name=".ASPXFORMSAUTH" loginUrl="~/Common/Login.aspx" timeout="450" />
</authentication>
<authorization>
<deny users="?" />
<allow roles="Admin" />
</authorization>
The configuration of all of this is via the web.config your membership and roles may be similar to this if you use the out of the box aspnetdb.
<membership defaultProvider="IDTSqlMembershipProvider" userIsOnlineTimeWindow="15">
<providers>
<clear />
<add
name="IDTSqlMembershipProvider"
type="System.Web.Security.SqlMembershipProvider"
connectionStringName="SqlMembershipConnectionString"
applicationName="ConsumerSynergy"
enablePasswordRetrieval="false"
enablePasswordReset="true"
requiresQuestionAndAnswer="false"
requiresUniqueEmail="true"
passwordFormat="Hashed"
maxInvalidPasswordAttempts="20"
minRequiredPasswordLength="6"
minRequiredNonalphanumericCharacters="0" />
</providers>
</membership>
<roleManager enabled="true" defaultProvider="IDTSqlRoleProvider" cacheRolesInCookie="true" cookieProtection="All">
<providers>
<clear/>
<add
name="IDTSqlRoleProvider"
type="System.Web.Security.SqlRoleProvider"
connectionStringName="SqlMembershipConnectionString"
applicationName="ConsumerSynergy"/>
</providers>
</roleManager>