Meaning and usage of עַל יְדֵי
In some sample sentences in Hebrew, I have seen the words עַל יְדֵי
From the context, it seems to be equivalent to the word "by" in English in the sense of "by doing something" as in the following sentences. Is this correct?

I practice Hebrew by speaking to myself.
אֲנִי מִתְאַמֵּן עִבְרִית עַל יְדֵי דִּבּוּר לְעַצְמִי.
aniy mit'amen iv'riyt al y'dey dibur l'atz'miy.

also
אֲנִי מִתְאַמֵּן בדוברי עִבְרִית עַל יְדֵי לְדַמְיֵן שֶׁאֲנִי מְדַבֵּר עִם יִשְׂרְאֵלִי.
I practice speaking Hebrew by imagining that I am speaking with an Israeli.

Some other sample sentences using עַל יְדֵי would be appreciated!

Question

Meaning and usage of עַל יְדֵי
In some sample sentences in Hebrew, I have seen the words עַל יְדֵי 
From the context, it seems to be equivalent to the word "by" in English in the sense of "by doing something" as in the following sentences. Is this correct?

I practice Hebrew by speaking to myself.
אֲנִי מִתְאַמֵּן עִבְרִית עַל יְדֵי דִּבּוּר לְעַצְמִי. 
aniy mit'amen iv'riyt al y'dey dibur l'atz'miy.

also
אֲנִי מִתְאַמֵּן בדוברי עִבְרִית עַל יְדֵי לְדַמְיֵן שֶׁאֲנִי מְדַבֵּר עִם יִשְׂרְאֵלִי.
 I practice speaking Hebrew by imagining that I am speaking with an Israeli.

Some other sample sentences using  עַל יְדֵי would be appreciated!

Answer

Hello Alexander,
As you wrote, the words על ידי in Hebrew are equivalent to the word "by" in English.
Your examples are good,but there are few corrections:
אֲנִי מִתְאַמֵּן בעִבְרִית עַל יְדֵי דִּבּוּר לְעַצְמִי
אֲנִי מִתְאַמֵּן בדיבור עִבְרִית עַל יְדֵי שאני מדַמְיֵן שֶׁאֲנִי מְדַבֵּר עִם יִשְׂרְאֵלִי.

another examples:
הדף נחסם על ידי גוגל.
The page has been blocked by Google.

העוגה הוכנה על ידי אחותי
The cake was prepared by my sister.

Answer

The second sentence is wrong.

You can't say "אני מתאמן בדוברי עברית"
That means: "I practice in Hebrew speakers"
Which makes no sence.

Try:
"אני מתאמן בעברית על ידי דיבור אל עצמי"
I practice Hebrew by speaking to myself

Hope it helped :)