Well, I downloaded the Halo 2 Elite Biped tags, uploaded by Delta4907, and when I go to select one of them, a window pops up saying:

Not all the selected tags could be added to the palette:
You selected one or more files that couldn't be loaded correctly.

Contact your nearest Bungie programmer for assistance.

And the debug said:

04.23.12 14:29:40 file_open('tags\delta4907\characters\h2elite\h2elite.gbxmodel') error 0x00000003 'The system cannot find the path specified. '
04.23.12 14:29:40 couldn't open gbxmodel tag 'h2elite.gbxmodel'.
04.23.12 14:29:40 file_open('tags\delta4907\characters\h2elite\h2elite.model_animations') error 0x00000003 'The system cannot find the path specified. '
04.23.12 14:29:40 couldn't open model_animations tag 'h2elite.model_animations'.
04.23.12 14:29:40 file_open('tags\delta4907\characters\h2elite\h2elite.model_collision_geometry') error 0x00000003 'The system cannot find the path specified. '
04.23.12 14:29:40 couldn't open model_collision_geometry tag 'h2elite.model_collision_geometry'.
04.23.12 14:29:40 file_open('tags\delta4907\characters\h2elite\shaders\shield plasma.shader_transparent_plasma') error 0x00000003 'The system cannot find the path specified. '
04.23.12 14:29:40 couldn't open shader_transparent_plasma tag 'shield plasma.shader_transparent_plasma'.
04.23.12 14:29:40 file_open('tags\characters\elite\elite melee.damage_effect') error 0x00000002 'The system cannot find the file specified. '
04.23.12 14:29:40 couldn't open damage_effect tag 'elite melee.damage_effect'.
04.23.12 14:29:40 file_open('tags\sound\dialog\elite\conditional\elite.dialogue') error 0x00000003 'The system cannot find the path specified. '
04.23.12 14:29:40 couldn't open dialogue tag 'elite.dialogue'.
04.23.12 14:29:40 file_open('tags\globals\elite.material_effects') error 0x00000002 'The system cannot find the file specified. '
04.23.12 14:29:40 couldn't open material_effects tag 'elite.material_effects'.
04.23.12 14:29:40 failed to load biped tag 'tags\delta4907\characters\h2elite\h2elite'

Could anyone tell me how to fix this?

they arent referenced correctly, i recommend getting hdoans h2 biped packs.

but if you insist on these, go into your h2elite biped and look for red text, those are things that are either missing or in a different folder, locate the missing tags and save the biped to fix.

Yeah, the main reason I picked Delta was because they came with Councilors and Guardsmen. But I'll get the Halo 2 v2 pack by HDoan. I'll get more with that, I guess. Thanks.