There is nothing wrong with a newb DM running a campaign.
It is easiest to do so as an Episodic campaign. Write a dungeon, turn them loose upon it. If they beat it, write a new one for the next session, turn them loose with it; if they didn't, let them continue against it.
A campaign, at its simplest, is a series of adventures with the same characters (or a majority of the same characters). As a new DM, you're likely to accidentally end a campaign... by accidental overkill.
Start small - one dungeon. And put it on a "regional" map with a town, a river, and some wilderness, and a road leading to a city. As you add dungeons, add them to that map. Add an extra town when you need it. Let them go back to known dungeons.
I'd suggest a blank piece of paper, and 1" = 8 miles (a day's hike on bad ground) to 36 miles (a hard day's march - people can hike 2 MPH comfortable on decent ground, and 3 MPH on roads).
Put your base "town" on the map, as a circle no more than 1/2 mile across - basically, a dot. Have a road run through it. Drop a smaller dot every 10-15 miles along the road. These are villages, probably with inns. Put some other terrain on in light colors - the town should have a river, which should run across the map.
The first dungeon should be half a day or less away. Mark it. Draw it up on separate paper... Run it. If they survive, add another nearby dungeon to the map, and draw it up, and run it. Poof! It's now a campaign! And, as you add new dungeons, have them further and further out. After the first couple, add travel across the region map as a prelude to the new dungeons.
There is an old guideline I'll share, derived from the old B/X/C/M series dungeons:
Level 1-3: Dungeons near base town, so you don't have more than one wilderness encounter per character level to get there.
Levels 4-6: dungeons a couple days travel away.
Levels 7-9: dungeons up to a couple weeks travel, or non-dungeon political adventures
levels 10-12: Dungeons up to a month's travel away, or on "nearby" planes. Political adventures near home. Start into the business of ruling.
Levels 13-15: dungeons on other planes, or where magic is needed to simply find it. Politics and rulership.
Heck, most 1st level dungeons can be "My cellar got invaded by _!" Go down, kill them all, and stop the problem. The dungeon isn't the cellar - it's the tunnels that broke into the dungeon. (The other end is outside the town).