I want to run a Tor server as an entry point of Tor network, so that the torstatus web page (torstatus.blutmagie.de) illustrate my server as a guard server. How do I accomplish this task?
You can't decide on your own to become a guard node. The Tor software makes the decision. All the details are laid out in Tor's directory specification.
So after you set up your Tor relay, it takes some time until it attracts traffic. Beginning on day 8 of your relay's lifetime it becomes eligible for the Guard flag. However getting the flag depends on the bandwidth, the uptime and the time it is known to the Tor network. So from my calculations on if your relay has more than 1,5MB/s bandwidth it can get the Guard flag. However this number might change and depends on the bandwidth of other guard nodes.
If you want the Guard flag for your relay, run it at least eight days, give it reasonable bandwidth and don't shut it down for longer periods of time. More details can be found at the blog post "life cyle of a new relay".
Tor does not let you decide whether to be a Guard or not by yourself. Since there are many security concerns with the Guard node, Tor has very strict conditions to flag a node as Guard node. For your ready reference, you can look at session "5. Guard nodes" of this Specification file.
Although Jens and Windy provided answers to your question, depending on your intentions, there maybe a short cut to create a specific type of guard you maybe interested in. This short cut does not publish your relay as guard in this Web site: 'torstatus.blutmagie.de' or any other Web site. However, you may use this type of guard as your own entry node if you so desire. This particular type of guards is named 'bridge' and none of the stringent requirement of becoming a guard apply to bridges. If this remedy help you, you may use this solution.