How to correctly use the Query API in AWS CloudWatch?

I am trying to query something from CloudWatch AWS. For this purpose I was following the documentation. I am getting an error response which says: "Could not find operation ListMetrics for version 2010-08-01"

Can anyone help me with it? I am appending the steps I am following (as of now manually):

Step 1: URI encode the following string:

GET\n monitoring.amazonaws.com\n /\n AWSAccessKeyId=DUMMYVALUEREPLACED &Action=ListMetrics &SignatureMethod=HmacSHA256 &SignatureVersion=2 &Timestamp=2015-03-26T09%3A05%3A00.000Z &Version=2010-08-01

I am using http://ift.tt/kngaFs for encoding.

Step 2: find the HMAC encoding of the string generated in step 1. Step 3: Convert the string generated in step 2 into a base64 format Step 4: URI encode the string generated in step 3 Step 5: Use string generated in Step 4 as the signature in the following string:

http://ift.tt/1D0SGKJ &Action=ListMetrics &Version=2010-08-01 &Timestamp=2015-03-26T09%3A05%3A01.000Z &AWSAccessKeyId= DUMMYVALUEreplaced &Signature= DUMMYVALUEreplaced

I am using the URL above in chrome browser.

Any ideas as to what am I doing wrong? I don't want to use the SDKs, so could you please help me use the Query API correctly?