Default "Activate Page/Asset" appears under "WCM Workflow" but if you are not able to see this component then i would suggest first check from design view if that component listed there and not selected, and if that also doesn't help then try to check this component configuration using crx/explorer or crx/de via going to location /libs/wcm/workflow/components/workflow/activateresourceprocess
I hope above will give you some direction, but if you still see some issue or not able to resolve it and need immediate solution then i would suggest to right your own process to publish the asset. You can refer replication api for same purpose http://dev.day.com/docs/en/cq/current/javadoc/com/day/cq/replication/package-summary.html.
Let me know if you need any informaiton related to custom implementation (i hope you dont require it ).
I have used the "Activate Page/Asset" process that appears under WCM Workflow.I am able to see in content repository that the uploaded document is activated.
Now my problem is about displaying the uploaded document.
If a user uploads a document and submits the form , this uploaded document is sent to the admin.Post Approval, the user should get a link to see the updated document.
Even though the asset(document) is activated , the user is not able to view it.
It pretty wierd, i would suggest to check below.
1. Check your replication queue whether queue is stucked? because in CQ the state of document immediatly change when the item placed in queue without checking the content is actually published or not (check here - http://<host>:<port>/etc/replication/agents.author.html also check the publish logs in agents.
2. Check the modify date of document if you have republished it next time on publish node.