If all you want is a sample database, the first steps create one for you or
go to a command line and do:
db2sampl <path>
A look at the db2 Command Reference on line helps or the following.

D:\SQLLIB\BIN>db2 ? create db
CREATE DATABASE database-name
[AT DBPARTITIONNUM | [AUTOMATIC STORAGE {NO | YES}]
[ON drive[{,drive}...][DBPATH ON drive]]
[ALIAS database-alias] [USING CODESET codeset TERRITORY territory]
[COLLATE USING {SYSTEM | IDENTITY | IDENTITY_16BIT | COMPATIBILITY |
NLSCHAR}]
[PAGESIZE integer [K]]
[NUMSEGS numsegs] [DFT_EXTENT_SZ dft_extentsize]
[CATALOG TABLESPACE tblspace-defn] [USER TABLESPACE tblspace-defn]
[TEMPORARY TABLESPACE tblspace-defn] [WITH "comment-string"]]
[AUTOCONFIGURE [USING config-keyword value [{,config-keyword value}...]]
[APPLY {DB ONLY | DB AND DBM | NONE}]]

tblspace-defn:
 MANAGED BY { SYSTEM USING ('string' [ {,'string'} ... ] ) |
 DATABASE USING ({FILE | DEVICE} 'string' number-of-pages
 [ {,{FILE | DEVICE} 'string' number-of-pages} ... ]) | AUTOMATIC STORAGE}
 [EXTENTSIZE number-of-pages] [PREFETCHSIZE number-of-pages]
 [OVERHEAD number-of-milliseconds] [TRANSFERRATE number-of-milliseconds]
 [NO FILE SYSTEM CACHING | FILE SYSTEM CACHING]
 [AUTORESIZE {NO | YES}] [INITIALSIZE integer {K |M |G}]
 [INCREASESIZE integer {PERCENT |K |M |G}] [MAXSIZE {NONE | integer {K |M

config-keyword:
 MEM_PERCENT, WORKLOAD_TYPE, NUM_STMTS, TPM, ADMIN_PRIORITY
 NUM_LOCAL_APPS, NUM_REMOTE_APPS, ISOLATION, BP_RESIZEABLE.

Once the db is created, a look at the SQL Refer. handbook will help in
defining yyour table spaces, tables an so on.

HTH,  Pierre.