What if I work with patients, or I am largely of different racial background than CEU and I want to determine the frequency of an allele?

You can go to this URL for the 1000 Genomes Project, https://www.ncbi.nlm.nih.gov/variation/tools/1000genomes/. On the left hand column, locate the "Ideogram VIew" section and look for the search box immediately below with the magnifying glass icon. Type your rsid# into the box and hit return. Then scroll down the page looking for the yellow highlighted column which contains the data for your rsid# and look for the ethnicity that most closely describes the population of interest. It is not an exhaustive list, but one of the most comprehensive to date.
CHB Han Chinese in Bejing, China
JPT Japanese in Tokyo, Japan
CHS Southern Han Chinese
KHV Kinh in Ho Chi Minh City, Vietnam
TSI Toscani in Italia
FIN Finnish in Finland
GBR British in England and Scotland
IBS Iberian population in Spain
YRI Yoruba in Ibadan, Nigera
LWK Luhya in Webuye, Kenya
GWD Gambian in Western Divisions in The Gambia
MSL Mende in Sierra Leone
ESN Esan in Nigera
ASW Americans of African Ancestry in SW USA
ACB African Caribbeans in Barbados
MXL Mexican Ancestry from Los Angeles USA
PUR Puerto Ricans from Puerto Rico
CLM Colombians from Medellin, Colombia
PEL Peruvians from Lima, Peru
GIH Gujarati Indian from Houston, Texas
PJL Punjabi from Lahore, Pakistan
BEB Bengali from Bangladesh
STU Sri Lankan Tamil from the UK
ITU Indian Telugu from the UK