Hi Vishnu,
Its not currently implemented to allow users to upload their own profile picture, though it is something I will implement at some point.
It is possible for an admin to upload user photos into the /Sites/[SiteID]/avatars folder and the admin can specify which photo is used for the user in user management.
There are some related Web.config settings and notes in Web.config
<!-- Gravatars
http://www.gravatar.com/ is a service that allows users to have the same Avatar across different sites.
I implemented support for this in mojoPortal 2008-08-13
I added this setting as a kill switch so that Gravatars can be disabled installation wide
in case there is ever a security or performance problem due to using this external service.
I don't expect any problems but just in case you can disable it here.
RatingType { G, PG, R, X } determine what rating is acceptable. Users rate their Avatars like movies.
-->
<add key="AllowGravatars" value="true" />
<add key="GravatarMaxAllowedRating" value="G" />
<!-- the old cheesy avatar system was just choices from a few cartoons
if you want to use it you can set AllowGravatars=false and set DisableOldCheesyAvatars=false
-->
<add key="DisableOldCheesyAvatars" value="true" />
<!-- you could replace the cheesy cartoon avatars with pictures of your staff/members but then you would want to set this to true
so only the admin user can pick the avatar, otherwise users would see a list of all the avatars and nothing forcesthem to choose the correct one.
-->
<add key="OnlyAdminsCanEditCheesyAvatars" value="false" />
Hope it helps,
Joe