I have the following troops are they a good start?
That is a pretty good start. The main thing you're missing is Farseers and anti-aircraft. You can convert or proxy the Farseers pretty easily. I'm assuming by "grav tanks" you mena primarily Falcons.
For reference, the Grand Tournament scenario is supposed to be balanced at 2000-5000 points. Most tourneys run 2700-4000, with 3000 being the most popular.
Assuming you convert up a handful of Farseers (3-4), you could build a 3,000 point infantry-heavy force with that and the only weakness would be that you'd be light on AA. You could actually throw down 4,000 points and be playable, though at that point level the lack of AA becomes a more substantial issue. If you add a few Wave Serpents or Storm Serpents for transport and some fighters or Firestorms for AA you could swing a competitive 5000 point army and still have enough extra to have some variety in army selection from game to game.
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As far as building it, I wouldn't trust Army Builder. For a few quick tips...
Typical small Guardian Hosts are 1 Farseer, 3-6 Guardians and 0-3 heavy weapon platforms.
Tricked out Guardian Hosts will add 3 Wraithguard and/or Wraithlords. Occasionally, you'll see a Guardian Host in Wave Serpents to do hit-and-run assaults, but that's usually reserved for Aspects.
Obviously, with Farseers, you can make a truckload of those. Light ones are under 200 points, heavy ones can top 350.
Aspect Hosts come in a few varieties. FF-oriented with mostly Dire Avengers or Warp Spiders and maybe a few Reapers or Dragons for some ranged fire to place BMs, CC-oriented with mostly Scorpions with maybe a couple FF types or ranged fire units for some extra flexibility, fast-attack Shining Spears or Swooping Hawks for relatively cheap, fast, hard-hitting formations, or fire support made primarily of Dark Reapers. The assault-oriented hosts have 1-2 Exarchs. They are sometimes mounted in Wave Serpents for transport, but that gets expensive quickly so rarely do you see more than one. More commonly, they use Wraithgates and Stormserpents for delivery mechanisms. The finer points of designing aspect hosts have been the topic of many threads on Epicomms.
You can do 2 CC hosts, a fire support host of Reapers/Dragons, and possibly a FF host with Warp Spiders and a few Reaper/Dragon leftovers. Based on packaging, it's very odd that there are no Dire Avengers in your list of units... maybe you mistook them for Guardians? They will normally be in the 350 point range, but with transport they'll be 550.
Windrider Troupes are usually fielded 1 of 3 ways - all Bikes, all Vypers, or Bikes with 1 (or 2) Vypers for a very small amount of firepower, mostly to place BMs. You can easily field 4 formations of various compositions at 200 points each.
Again assuming the "grav tanks" are primarily Falcons, you have enough for a couple formations of armor support at 250 points each.
Up to 1/3 of the army can be spent on titans and aircraft, so you have enough titans to do all sorts of combinations.
