This tutorial will get you using Swarm productively in minutes! First get Swarm running as described on the download page or in Section I of the manual.
By default Swarm is set to open a window that will fit on a 1024x768 screen but IT IS NOT INTENDED TO BE USED AT THIS RESOLUTION! Maximize the window; make it as big as possible! Helicorders are big, they display lots of data, use the whole monitor!
Create a data source. Unless you want to look at AVO data you'll have to tell Swarm where to look for data. Click 'New' on the Data Sources panel in the upper left of the Swarm interface. For non-AVO users you're option is an Earthworm Wave Server. Pick a name for your data source (like 'My Wave Server'), enter the IP address or host name, and set the port (16022 by default). After you hit 'OK' the data source will appear in the selection box. Highlight it and click 'Go'.
Start downloading some helicorder data. Since you'll be running off a Wave Server you need to download data before you can display a full helicorder (Winston users won't have to wait, of course), so click on the 'Helicorders' tab and pick a channel. Either double-click it or click 'View Helicorder'. A blank helicorder window should open with a bit of data at the bottom. Swarm has now started downloading some data. Give it 30 seconds to a minute and more will show up until it fills up the whole helicorder (time varies by network connection, wave sample rate, etc.). In the mean time, try some other features (see Step 3).
Try out a real-time wave viewer. Highlight a random channel on the 'Waves' tab and double-click it or click 'Real-time'. This will open a window that shows the last two minutes of data, updated every two seconds. Try a spectrogram or spectra view by clicking on the appropriate button on the toolbar. In reality, this is probably the least exciting feature of Swarm, but hopefully you'll play with it long enough to have downloaded some data for the helicorder.
Play with the helicorder. Now that you've got some data on your helicorder you can use the mouse to look at it closely. Just left-click or drag your mouse (with left button down) to display the raw waveform behind an interesting feature on the helicorder. You can then use the buttons at the top of the helicorder to change the wave view. Or modify the size and shape of your helicorder. If you increase the size of the Y axis Swarm will start downloading more data. Also, don't be afraid to close the helicorder, Swarm automatically keeps a cache of all recent data -- if you reopen the channel the helicorder will appear instantly.
Try the Wave Clipboard. If you found something interesting on the helicorder then copy it to the clipboard (look for a clipboard button on the right side of the toolbar, or just type 'C'). There you can zoom around the wave all you like, make copies of it to try different filters on, or load other stations in the same time window (clicking 'Clipboard' on the Channel Selection panel automatically chooses the time range of the selected [blue] wave on the clipboard).
The manual explains all of the features of Swarm in detail.