6 fighters 2 dive bombers is a pretty standard setup.

if you lvl the pilots in 2 goes, might wanna add another couple of bombers to have some fun in blitz (and get the 2nd cv line as well)

might add seaman as well for the later tier cv's

you might take a look at the tips & tactics for that, or the IJN section, theres a cv info topic over there as well, detailed per cv etc.

point is low lvl cv's run fewer pilots (5 or 6) as big ones (8 pilots + 1 support slot), but you need to level those crews either way, so starting a second cv line is a way to do that.
adding to that, playing cv trough blitz is pretty fun.

for small cv's in blitz i'd recommend 2 dive bombers, rest scout or fighter
for small cv's in GB i'd recommend a similar setup
(since you cant take on higher fighters with yours, and you gain more XP trough bombing)
for higher tier cv's you need a fighter heavy setup to rotate fighters around the field.
(leveling up 2  cv crews will actually allow you to run both setups if you plan ahead)

you can also run 4 FP / 4 DB or 6 FP / 2 DB, depending on your playing style.
i prefer low loading times & more squadrons of fighters, since i hardly use bombers
but i also know people that are more keen on bombing and prefer more DB pilots.

on the R slots you'd be best of with either DP gunners or normal gunners, since you need the normal gunners to level up to get to your cv level. since IJN AA on cv's isn't very usefull (imo Hedge hogs for ASW work best) i wouldnt go for the DP gunners, but just keep leveling the normal gunners. 

use the search function for more info on cv's there's plenty on here.

I still didn't understand how will 2nd CV line will help me,can you explain in to me in simpler English? It's a foreign language to me.
And the only way to choose 2 CV lines is by 2 BOs right?

 

The 2nd CV line will help you level your sailors for your first CV line. You will not have enough sailor slots on your CV to level all of your pilots on at low levels. Pilots also gain less experience than other sailors, so your BO will eventually become higher than your pilots.

 

Skelaitize a BO or two

6 or 8 FP 

6 or 8 DB 

2 Seamen

2 gunners if you want... completely optional 

And various supports based on what you like... only reps and engines 

Optimal cv setup 


Also about the second BO its purpose is to get access to all the good cvs that IJN have in the 2 lines, And to keep your sailors at a higher lvl than your B.O. so that way you wont be hindering your team with being in a higher lvl cv with lower lvl pilots.

Also CV Bo's don’t need anything really...unless you plan to reset to a bb line. Its best to keep them at 0 Recruits 0 Experts and 0 Vets... 

 

People told me to get 6 FPs,2 DBS,Seaman,2 Gunners,BO...

8 FP and 8 Db lets you do what ever you want wether it be dbw or fw and anything inbetween..... you probaly want atleast 1 seaman 2 would be better... gunners are completly optional most of the time people tend to drop 2 rep's in the R slots which works well... Also having at least one engy would be a good thing